Sami al-Askari, aide to Nuri al-Maliki, the Iraqi prime minister, said: "There is a race between the government and the terrorists who are trying to make people reach the level of despair.
"But the government is doing its best to defeat terrorists and it definitely will not be affected by these bombings."
Drop in violence
Iraqi police said that 26 people were killed or found dead on Friday, a big decrease from the 181 who died on Thursday, most of them in suicide attacks north of Baghdad.
The US military said one soldier was killed and a second wounded on Thursday during a patrol in southern Baghdad, raising to at least 3,245 the number of US service members who have died since the war began in 2003, according to an Associated Press count.
In other incidents, the US army said that its forces arrested 11 people on Friday described as "terrorists" in a raid in the Anbar province, west of Baghdad.
Iraqi police also said that US and Iraqi forces arrested dozens of the people who were praying after surrounding a mosque in the al-Dura district, south of Baghdad.
Meanwhile, Moqtada al-Sadr, the Shia leader who heads the Sadrist movement, has again called for the US to pull out of Iraq.
Al-Sadr's statement on Friday was his first since March 14, when he urged supporters to resist US forces in Iraq through peaceful means.
"The chances of success [in Iraq] are essentially zero because the Iraqi people have no voice"
Non Sequitur, Cadiz, Spain
Send us your viewsHe said: "The departure of the occupier will mean stability for Iraq, victory for Islam and peace and defeat for terrorism and infidels."
US and Iraqi officials have said al-Sadr remains in Iran, but other sources claim he has returned to Najaf.
"I renew my call for the occupier [the United States] to leave our land," he said in the statement.
For his part, General David Petraeus, the US commander in Iraq, issued a statement blaming al-Qaeda in Iraq for the week's first major suicide attack, a twin truck bombing that killed 80 people and wounded 185 in Tal Afar in the northwest of the country.
He said the al-Qaeda sponsors of the suicide attack "once again displayed their total disregard for human life, carrying out barbaric actions against innocent Iraqi citizens in an effort to re-ignite sectarian violence and to undermine recent Iraqi and coalition successes in improving security in Baghdad".
Also on Friday, the US welcomed Japan's two-year extension of its air force's airlift mission in support of reconstruction in Iraq.
"The Japanese forces have been very important in providing logistical and air support into Iraq," Sean McCormack, the state department spokesman, said.
The Japanese Diet extended the mission on Friday for two additional years. It was to have ended on July 31.
Flying from Kuwait, the Japanese aircraft are ferrying supplies and personnel into Iraq from neighbouring Kuwait.